Fabrication and characterization of piezoelectric driven microdiaphragm resonating sensor for a biosensing application

The detection capability of microresonating sensors is decided by the resonant properties (mass sensitivity and quality factor) because the microresonating sensors have detection principle that the target material of small amount quantitatively detect by measuring the resonant properties change of microresonators. Mass sensitivity is important factor to evaluate minimum detectable mass of microresonating sensors. For the biomolecule detection in liquid, microresonaotrs have to keep the quality factor that can discriminate small frequency change when the liquid sample injected on the microresonating sensors. In order to study mass sensitivity and quality factor of the fabricated microdiaphragm sensors, Pt thin film with different thicknesses are deposited on the our Pb(Zr_0.52Ti_0.48)O₃ layer-embedded microdiaphragm sensors. Increasing the mass sensitivity ranging from 1.68 to 36.61 Hz/ng which is found with the decreasing the width of squared microdiaphragms ranging 900 to 300 μm. The mass sensitivity of our microdiaphragm sensor stands comparison with microcantilever sensor of length scale of 200 ~ 300 μm. Moreover, we find that the quality factor is kept on more than 23 that was ten times better than microcantilever resonating sensor with length scale of 200 μm.